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Article
Publication date: 1 April 2004

T.S. Lee, Y.G. Liu and S.H. Winoto

Numerical studies are carried out to investigate the liquid‐lubricated herringbonegrooved journal bearings (HGJBs) performance (such as the pressure and cavitation…

Abstract

Numerical studies are carried out to investigate the liquid‐lubricated herringbonegrooved journal bearings (HGJBs) performance (such as the pressure and cavitation distribution, load capacity and attitude angle, stability, etc.). Symmetrical and non‐symmetrical HGJBs are studied, respectively, and the herringbone grooves' influence on the stability of HGJBs is analyzed carefully. It was found that the maximum pressure and load capacity increase with the increase of eccentricity ratio while the attitude angle decreases with the increase of eccentricity ratio. The cavitation may occur in the fluid film of journal bearings while the eccentricity ratio increases to some critical value. The area of cavitated region increases with the increase of the eccentricity ratio. For non‐symmetrical HGJBs, the pressure and cavitation distribution is asymmetrical oo.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 14 no. 3
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 August 2002

Wan Junmei, T.S. Lee, C. Shu and Wu Jiankang

A numerical model is presented in this paper to better describe the cavitated fluid flow phenomena in liquid‐lubricated Asymmetrical Herringbone Grooved Journal Bearings…

Abstract

A numerical model is presented in this paper to better describe the cavitated fluid flow phenomena in liquid‐lubricated Asymmetrical Herringbone Grooved Journal Bearings (HGJBs). An effective “follow the groove” grid transformation method is used in the present study to capture all the groove boundaries. A singularity at the groove edges is avoided with this approach. Symmetrical groove patterns as well as asymmetrical groove patterns can be accurately computed with the proposed method. The difficult problem of abrupt changes of oil film thickness in the liquid‐lubricated HGJB physical domain is modeled here through a series expansion approach. Results are comparable with available experimental and known numerical data from other investigators. Cavitation footprints, pressure distributions and their corresponding load characteristics are presented in this study. Effects of the critical transitional flow phenomena on the performance of the asymmetrical HGJBs are also determined through the present study.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 12 no. 5
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 4 March 2014

Zhang Guo-yuan, Wei-gang Zhao and Yan Xiu Tian

A new type of hydrostatic and hydrodynamic non-contacting face seals has been designed to meet the requirements of lower leakage, longer life and more repeatedly start and…

Abstract

Purpose

A new type of hydrostatic and hydrodynamic non-contacting face seals has been designed to meet the requirements of lower leakage, longer life and more repeatedly start and stop on shaft seals raised by liquid rocket engine turbopumps. And an experimental study on the performance of the face seal in the actual liquid oxygen turbopump was completed where low-viscosity water was selected as the seal fluid for the sake of safety. The paper aims to discuss these issues.

Design/methodology/approach

Different performances of face seals under preset conditions were obtained by repeatedly running tests, and the main performance parameters encompass leakage, fluid film pressure between the faces, operating power, face temperature, and so on.

Findings

The results indicate that the designed face seal has a smaller amount of leakage, with a minimum value of 3 ml/s. Furthermore, the designed face seal has been proved to demand lower operating power. Since its operating power changes slightly with different sealed fluid pressures, the new seal can be deployed in the harsh working condition with high pressure or with high speed (greater than 20,000 rpm). However, one proviso is that when liquid is employed as the seal fluid, the groove depth should be relatively deeper (greater than 10 μm).

Research limitations/implications

In response to future engineering requirements, study on the controllable spiral-groove face seals to improve the current design is being conducted.

Originality/value

The advancement of such non-contacting face seals proffers important insights to the design of turbo-pump shaft seal in a new generation of liquid rocket engine with regard to the requirement of frequent start and stop as well as long life on it.

Details

Industrial Lubrication and Tribology, vol. 66 no. 2
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 22 September 2021

Lei Yin, Xiaolin Zheng, Dongxing Tang, Yanfeng Han, Rui Zhao and Yi Chen

This study aims to develop a new method to treat the numerical singularity at the critical nodes of two skew coordinates, and optimize the leakage of micro herringbone

Abstract

Purpose

This study aims to develop a new method to treat the numerical singularity at the critical nodes of two skew coordinates, and optimize the leakage of micro herringbone grooved journal bearings (MHGJBs) with this method.

Design/methodology/approach

A side leakage numerical algorithm is proposed by using the skew meshes with a virtual node (SMVN) method to evaluate the effects of groove angle, bank/groove ratio, groove depth and groove number on load capacity, friction and side leakage of MHGJB.

Findings

The SMVN method is effective in treating the numerical singularity at the critical nodes of two skew coordinates. Besides, a group of optimized parameters of micro herringbone groove is obtained which can not only minimize the side leakage but also improve the load capacity and friction force.

Originality/value

A virtual node method was proposed, which can significantly improve the calculation accuracy in the side leakage model.

Details

Industrial Lubrication and Tribology, vol. 73 no. 7
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 16 August 2011

Cheng‐Chi Wang

This paper employs a hybrid numerical method combining the differential transformation method (DTM) and the finite difference method (FDM) to study the bifurcation and…

Abstract

Purpose

This paper employs a hybrid numerical method combining the differential transformation method (DTM) and the finite difference method (FDM) to study the bifurcation and nonlinear behavior of a rigid rotor supported by a relative short gas lubricated journal bearing system with herringbone grooves. The analysis reveals a complex dynamic behavior comprising periodic, subharmonic and quasi‐periodic responses of the rotor center. The dynamic behavior of the bearing system varies with changes in the rotor mass and bearing number. The current analytical results are found to be in good agreement with those of other numerical methods. This paper discusses these issues.

Design/methodology/approach

In this paper, DT is used to deal Reynolds equation and is also one of the most widely used techniques for solving differential equations due to its rapid convergence rate and minimal calculation error. A further advantage of this method over the integral transformation approach is its ability to solve nonlinear differential equations. In solving the Reynolds equation for the current gas bearing system, DTM is used for taking transformation with respect to the time domain τ, and then the FDM is adopted to discretize with respect to the directions of coordinates.

Findings

From the Poincaré maps of the rotor center as calculated by the DTM&FDM method with different values of the time step, it can be seen that the rotor center orbits are in agreement to approximately four decimal places for the different time steps. The numerical studies also compare the results obtained by the SOR&FDM and DTM&FDM methods for the orbits of the rotor center. It is observed that the results calculated by DTM&FDM are more accurately than SOR&FDM. Therefore, the DTM&FDM method suits this gas bearing system and provides better convergence than SOR&FDM method.

Originality/value

This study utilizes a hybrid numerical scheme comprising the DTM and the FDM to analyze nonlinear dynamic behavior of a relative short gas lubricated journal bearing system with herringbone grooves. The system state trajectory, phase portraits, the Poincaré maps, the power spectra, and the bifurcation diagrams reveal the presence of a complex dynamic behavior comprising periodic, subharmonic and quasi‐periodic responses of the rotor center. Therefore, the proposed method provides an effective means of gaining insights into the nonlinear dynamics of relative short gas lubricated journal bearing systems with herringbone grooves.

Details

Industrial Lubrication and Tribology, vol. 63 no. 5
Type: Research Article
ISSN: 0036-8792

Keywords

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Article
Publication date: 2 October 2007

W. Ochoński

This paper seeks to present some new designs of sliding bearings lubricated with magnetic fluids (ferrofluids) and the possibility of using them in modern bearing…

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Abstract

Purpose

This paper seeks to present some new designs of sliding bearings lubricated with magnetic fluids (ferrofluids) and the possibility of using them in modern bearing technology, in new computer and audiovisual equipment among others.

Design/methodology/approach

The paper presents new designs of journal, thrust and journal‐thrust sliding bearings lubricated and sealed with magnetic fluids such as: magnetic fluid bearing bushing made of magnetizable material, pivot bearings with porous sleeve impregnated with ferrofluid, self‐aligning bearings, hydrodynamic ferrofluid bearings with spiral and herringbone grooves structure are presented. Moreover, examples are shown of applications in modern bearing technology.

Findings

The paper provides information about new designs of magnetic fluid sliding bearings assemblies and gives the main advantages of these bearings over conventional ball bearings, such as extremely low non‐repetitive run‐out (high‐accuracy of rotation), good damping and quietness of operation, maintenance free service and high reliability.

Originality/value

This paper offers some new designs of compact, low friction and self‐contained magnetic fluid sliding bearings and points up their practical applications.

Details

Industrial Lubrication and Tribology, vol. 59 no. 6
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 26 March 2021

Shicheng Yan, Yahong Xue, Liming Wei and Zhanchao Wang

This paper aims to elucidate the effects of lubricant groove shape, vertical load, swing angle and grease injection cycle on the friction and wear performances of journal…

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Abstract

Purpose

This paper aims to elucidate the effects of lubricant groove shape, vertical load, swing angle and grease injection cycle on the friction and wear performances of journal bearings under the grease lubrication condition.

Design/methodology/approach

Three different types of lubricant grooves, namely, numeral eight-shaped, axial straight line-shaped and circular blind hole-shaped, were designed and machined in the bearing bush of journal bearings. The tribological behaviors of these journal bearings were investigated on the self-developed reciprocating swing friction and wear tester. Experimental data including the friction coefficient, the friction temperature, the wear loss and wear time were analyzed in detail. The wear morphologies of friction pairs were observed by scanning electron microscope and confocal laser scanning microscope.

Findings

The load carrying capacity and service life of the journal bearing with circular blind hole-shaped lubricant grooves are not affected. However, the load carrying capacities of journal bearings with numeral eight-shaped and axial straight line-shaped lubricant grooves are declined. The coverage areas of lubricating grease in the bearing bush are associated with the swing angle. The smaller the swing angle is, the more limited the coverage areas of lubricating grease get. Among these journal bearings, the maintenance-free time of journal bearing with circular blind hole-shaped lubricant grooves is the longest because of its large grease storage capacity.

Originality/value

The journal bearing with circular blind hole-shaped lubricant grooves exhibits the excellent antifriction and wear-resistant properties, making it suitable for the application in the low-speed and heavy-load engineering conditions.

Details

Industrial Lubrication and Tribology, vol. 73 no. 3
Type: Research Article
ISSN: 0036-8792

Keywords

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Article
Publication date: 6 December 2019

Xiumin Zhang, Mingfu Yin and Huilai Sun

This paper aims to study the dynamic characteristics of the straight-through labyrinth seals, which is applied on an oil sealing belt of hydrostatic support system (HSS…

Abstract

Purpose

This paper aims to study the dynamic characteristics of the straight-through labyrinth seals, which is applied on an oil sealing belt of hydrostatic support system (HSS) oil pocket, the establishment and solution process of seal governing equation is deduced.

Design/methodology/approach

The three-control-volume model theory is an efficient approach that is applied well. This paper starts with three relative governing equations for the flow characteristics of straight-through labyrinth seals in the plane direction. Referring to the establishment process of governing equations for circumferentially-grooved liquid seals, the governing equation based on space rectangular coordinate system is established, which are transformed into dimensionless equations through a nondimensionalized process and solved by a perturbation method. It contains a zeroth-order equation, through which a steady fluid distribution is determined, and a first-order equation, through which the seal’s dynamic coefficients can be acquired.

Findings

The governing equation for plane-grooved straight-through labyrinth seals can be established and solved by the three-control-volume theory.

Practical implications

This study have important guiding significance for further theoretical research and structural design of the straight-through labyrinth seals on the oil sealing belt of HSS oil pocket.

Originality/value

In this paper, a straight-through labyrinth seal is installed in an oil sealing belt. The three-control-volume governing equations is established in space rectangular coordinate system, and the shear force of the fluid Y-direction is different from the previous model.

Details

Industrial Lubrication and Tribology, vol. 72 no. 3
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 29 May 2019

Penggao Zhang, Boqin Gu, Jianfeng Zhou and Long Wei

The purpose of this study is to investigate the heat transfer characteristics in a spiral groove mechanical seal lubricated by magnetic fluid.

Abstract

Purpose

The purpose of this study is to investigate the heat transfer characteristics in a spiral groove mechanical seal lubricated by magnetic fluid.

Design/methodology/approach

The viscosity relationship of magnetic fluid in external electromagnetic field was deduced. The temperature distribution of sealing ring was calculated by the method of separation variables.

Findings

It has been found that the rotating ring absorbs most friction heat. The temperatures on the end faces of rotating ring and stationary ring decrease from inner radius to outer radius, the temperature of magnetic fluid film decreases from rotating ring to stationary ring and the highest temperature of the sealing system is at the junction of the inner radius and the end face of rotating ring.

Originality/value

Selecting the sealing rings with higher thermal conductivity and reducing the volume fraction of solid particles in magnetic fluid can reduce the temperature of sealing system effectively.

Details

Industrial Lubrication and Tribology, vol. 71 no. 6
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 20 August 2021

Mojtaba Zeraatkar, Marco Donato de Tullio, Alessio Pricci, Francesco Pignatelli and Gianluca Percoco

The purpose of this study is to introduce an alternative construction for microfluidic micromixers, where the effect of the extruded filaments in the fused deposition…

Abstract

Purpose

The purpose of this study is to introduce an alternative construction for microfluidic micromixers, where the effect of the extruded filaments in the fused deposition modeling (FDM) technique is used to enhance mixing performance identified as a challenge in microfluidic micromixers.

Design/methodology/approach

A simple Y-shaped micromixer was designed and printed using FDM technique. Experimental and numerical studies were conducted to investigate the effect of the extruded filaments on the flow behavior. The effects of the extruded width (LW), distance between adjacent filaments (b) and filament height (h1) are investigated on the mixing performance and enhancing mixing in the fabricated devices. The performance of fabricated devices in mixing two solutions was tested at flow rates of 5, 10, 20, 40, 80 and 150 µL/min.

Findings

The experimental results showed that the presence of geometrical features on microchannels, because of the nature of the FDM process, can act as ridges and generate a lateral transform through the transverse movement of fluids along the groove. The results showed the effect of increasing ridge height on the transverse movement of the fluids and, therefore, chaotic mixing over the ridges. In contrast, in the shallow ridge, diffusion is the only mechanism for mixing, which confirms the numerical results.

Originality/value

The study presents an exciting aspect of FDM for fabrication of micromixers and enhance mixing process. In comparison to other methods, no complexity was added in fabrication process and the ridges are an inherent property of the FDM process.

Details

Rapid Prototyping Journal, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1355-2546

Keywords

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